Liquid crystal display devices are common display devices, and prevail because of the features of low power consumption, small volume and lightweight. The liquid crystal display device usually comprises a backlight module and a display panel. The backlight module is used to provide surface light for the display panel. The backlight module usually comprises a light guide plate and a light source. The light source is usually arranged at the two opposite sides of the light guide plate to provide light to the light guide plate. The light guide plate is used to transform the light emitted from the light source as surface light. When there is expansion to the light guide plate because of being heated or absorbing moisture, the light guide plate extrudes the light source arranged at the tow opposite sides to further damage the light source. Or the light guide plate extrudes the light source arranged at the tow opposite sides of the light guide plate such that the light guide plate is damaged.